title: Invasion potential and N-acetylgalactosamine expression in a human melanoma model.
abstract: Reactivity of the N-acetylgalactosamine-binding Helix pomatia agglutinin (HPA) in tumours has been associated with poor prognosis and metastasis development. In our LOX/FEMX-I human melanoma model, the binding of HPA correlates with experimental lung metastasis formation in athymic nude mice. In the present study, the metastatic potential of 2 human melanoma cell lines (LOX and FEMX-I) was assessed in relation to carbohydrate and invasive phenotype. Immunocytological and invasion assays highlighted significant differences between these 2 cell lines. Immuno-cytochemical analysis confirmed the widespread expression of HPA-binding glycoconjugates on LOX but not FEMX-I cells. One of these HPA-binding glycoconjugates, the Tn antigen, was expressed highly on the surface of LOX cells but only weakly in the cytoplasm of FEMX-I cells. The sialyl Tn antigen was expressed in FEMX-I but not in LOX cells. There was no difference between the cell lines in adhesion/rate of trapping in athymic nude mouse lung tissues. In Matrigel invasion assays, LOX cells demonstrated an invasion potential more than 6 times greater than that observed with FEMX-I cells. Matrigel invasion of LOX cells was inhibited after incubation with HPA (89%) compared to controls with HPA and GalNAc blocking sugar or without HPA (p < 0.0005 at 5 df). In contrast, there was no inhibitory effect with the anti-Tn antibody IE3. Invasion of FEMX-I cells was not affected by the lectin and the IE3 antibody. Immuno-cytochemical analysis revealed expression of the terminal galactose- and polylactosamine-binding lectin galectin 3 (Mac-2) in these melanoma cell lines. Expression of both the lectin and its receptor may be a contributory feature in the pulmonary invasion of LOX melanoma cells. Overall, our findings suggest that HPA-binding glycoconjugates other than the alphaGalNAc-O-Ser/Thr of the Tn antigen may be important in the extracellular matrix invasion of LOX melanoma cells.
authors.affiliation: Department of Tumour Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo. prye@radium.uio.no
authors.forename: P D
authors.initials: PD
authors.lastname: Rye
authors.forename: O
authors.initials: O
authors.lastname: Fodstad
authors.forename: E
authors.initials: E
authors.lastname: Emilsen
authors.forename: M
authors.initials: M
authors.lastname: Bryne
mesh_terms: D000116:Acetylgalactosamine / Q000378:metabolism*; D000818:Animals; D000943:Antigens, Differentiation / Q000502:physiology; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000378:metabolism; D003094:Collagen; D004338:Drug Combinations; D037502:Galectin 3; D006001:Glycoconjugates / Q000378:metabolism; D006801:Humans; D007797:Laminin; D008175:Lung Neoplasms / Q000473:pathology / Q000556:secondary; D008545:Melanoma / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D011509:Proteoglycans; D014183:Transplantation, Heterologous
chemical_list: D000943:Antigens, Differentiation; D015295:Antigens, Tumor-Associated, Carbohydrate; D004338:Drug Combinations; D037502:Galectin 3; D006001:Glycoconjugates; D007797:Laminin; D011509:Proteoglycans; C040286:Tn antigen; C059485:matrigel; D003094:Collagen; D000116:Acetylgalactosamine